# -*- coding: utf-8 -*- 
""" 
Created on Wed Sep 27 15:47:54 2017 
 
@author: tina 
""" 
import cv2 
import numpy as np 
 
camera = cv2.VideoCapture(0) # 參數(shù)0表示第一個攝像頭 
# 判斷視頻是否打開 
if (camera.isOpened()): 
  print('Open') 
else: 
  print('攝像頭未打開') 
 
# 測試用,查看視頻size 
size = (int(camera.get(cv2.CAP_PROP_FRAME_WIDTH)), 
    int(camera.get(cv2.CAP_PROP_FRAME_HEIGHT))) 
print('size:'+repr(size)) 
 
es = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (9, 4)) 
kernel = np.ones((5, 5), np.uint8) 
background = None 
 
while True: 
  # 讀取視頻流 
  grabbed, frame_lwpCV = camera.read() 
  # 對幀進(jìn)行預(yù)處理，先轉(zhuǎn)灰度圖，再進(jìn)行高斯濾波。 
  # 用高斯濾波進(jìn)行模糊處理，進(jìn)行處理的原因：每個輸入的視頻都會因自然震動、光照變化或者攝像頭本身等原因而產(chǎn)生噪聲。對噪聲進(jìn)行平滑是為了避免在運(yùn)動和跟蹤時將其檢測出來。 
  gray_lwpCV = cv2.cvtColor(frame_lwpCV, cv2.COLOR_BGR2GRAY) 
  gray_lwpCV = cv2.GaussianBlur(gray_lwpCV, (21, 21), 0) 
 
  # 將第一幀設(shè)置為整個輸入的背景 
  if background is None: 
    background = gray_lwpCV 
    continue 
  # 對于每個從背景之后讀取的幀都會計算其與北京之間的差異，并得到一個差分圖（different map）。 
  # 還需要應(yīng)用閾值來得到一幅黑白圖像，并通過下面代碼來膨脹（dilate）圖像，從而對孔（hole）和缺陷（imperfection）進(jìn)行歸一化處理 
  diff = cv2.absdiff(background, gray_lwpCV) 
  diff = cv2.threshold(diff, 148, 255, cv2.THRESH_BINARY)[1] # 二值化閾值處理 
  diff = cv2.dilate(diff, es, iterations=2) # 形態(tài)學(xué)膨脹 
  # 顯示矩形框 
  image, contours, hierarchy = cv2.findContours(diff.copy(), cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE) # 該函數(shù)計算一幅圖像中目標(biāo)的輪廓 
  for c in contours: 
    if cv2.contourArea(c) < 1500: # 對于矩形區(qū)域，只顯示大于給定閾值的輪廓，所以一些微小的變化不會顯示。對于光照不變和噪聲低的攝像頭可不設(shè)定輪廓最小尺寸的閾值 
      continue 
    (x, y, w, h) = cv2.boundingRect(c) # 該函數(shù)計算矩形的邊界框 
    cv2.rectangle(frame_lwpCV, (x, y), (x+w, y+h), (0, 255, 0), 2) 
 
  cv2.imshow('contours', frame_lwpCV) 
  cv2.imshow('dis', diff) 
 
  key = cv2.waitKey(1) & 0xFF 
  # 按'q'健退出循環(huán) 
  if key == ord('q'): 
    break 
# When everything done, release the capture 
camera.release() 
cv2.destroyAllWindows()